1. Field of the Invention
The present invention relates to a workpiece holder for clean container and, more particularly to such a workpiece holder, which is practical for use in a clean container to hold workpieces horizontally in position.
2. Description of Related Art
In semiconductor foundries, produced wafers are horizontally arranged in a cassette, which has supporting flanges for holding a number of wafers in horizontal. The cassette can be mounted on the base of a wafer container, for example, a POD or FOUP, and then covered by the housing of the wafer container for transfer. The housing protects wafers against contamination.
When carrying the wafers in the cassette inside the wafer container, wafers may displace during transfer of the wafer container. In order to eliminate this problem, a positioning structure is used in the wafer container. When covering the housing of the wafer container on the cassette on the base, a slide is against at the base of the wafer container, and then the base pushed the slide and to move a holder member forwards, causing the holder member to hold down loaded wafers. According to this design, a friction is produced between the slide and the base when the base pushing the slide, and such friction causes particles that may contaminate loaded wafers.
Except the aforesaid wafer container, some other clean containers for carrying photo masks, glass substrates, and other workpieces may have the same problem.